Self serve car wash systems may be designed either for manual operation by manually moving a wand to first direct a high pressure spray of a detergent solution over the vehicle and then to direct a rinse spray of water over the vehicle, or the systems may be designed to automatically spray the vehicle with detergent and rinse water. Attention is directed to the automatic car wash system shown in U.S. Pat. No. 3,496,908 to Bernardi, the disclosure of which is incorporated herein. In that system, a vehicle is positioned under a generally rectangular overhead track which is larger than the plan dimensions of the vehicle. A motor drives a trolley along the track to move the trolley around the vehicle. As the trolley moves around the vehicle, a plurality of arms mounted on the trolley are rotated above the vehicle about a vertical axis. Nozzles on the rotating arms direct a high pressure spray at the top surfaces of the vehicle. A Second plurality of arms mounted on the trolley are rotated next to the side of the vehicle about a horizontal axis. Nozzles on the rotating second arms direct a high pressure spray at the sides of the vehicle. The trolley may be advanced around the vehicle four times during a cleaning cycle. During the first pass around the vehicle, a pre-soak detergent is applied to the vehicle at a relatively low pressure. During the second pass around the vehicle, detergent is directed at the vehicle surfaces at a high pressure. The revolving nozzles and the high fluid pressure produce a maximum impact to loosen dirt and film. During the third pass around the vehicle, a foamed wax may be applied to help break down the detergent and suspended soil on the vehicle. During the fourth pass around the vehicle, a high pressure clear water rinse is directed at the vehicle to remove all of the emulsified soils suspended during the previous steps. In areas which produce high dissolved solids, an optional fifth pass may be used to provide a spot free rinse for the vehicle.
Systems of the above described type provide a high quality cleaning. However, the quality of the cleaning will decrease as the spacing from the high pressure rotating nozzles to the vehicle surfaces increases. In particular, the cleaning efficiency on the sides of the vehicle will diminish with increase in the nozzle to vehicle surface spacing. A channel or track is formed at the floor on the drivers side of the vehicle under the overhead track. This channel guides the drivers side vehicle wheels to position the vehicle under the overhead track. A detector is mounted on the floor track for indicating when the drivers side front wheel is properly positioned with the vehicle under the overhead track. The width of the overhead track must be sized to accept the largest sized vehicles to be cleaned by the system. Consequently, for smaller vehicles, the rotating side cleaning nozzles can have an undesirably large spacing from the vehicle side and rear furthest from the wheel which is used to position the vehicle in the cleaning station.